/*
 * Tigase Jabber/XMPP Utils
 * Copyright (C) 2004-2012 "Artur Hefczyc" <artur.hefczyc@tigase.org>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. Look for COPYING file in the top folder.
 * If not, see http://www.gnu.org/licenses/.
 *
 * $Rev$
 * Last modified by $Author$
 * $Date$
 */
package tigase.util;

import java.security.SecureRandom;
import java.security.SecureRandomSpi;

/**
 * Describe class VMPCRandom here.
 * 
 * 
 * @author <a href="mailto:bmalkow@tigase.org">Bartosz Malkowski</a>
 * @version $Rev$
 */
public class VMPCRandom extends SecureRandom {

	public static class Spi extends SecureRandomSpi {

		private static final long serialVersionUID = 6772408791281461866L;

		private byte n = 0;

		private byte[] P = { (byte) 0x76, (byte) 0xae, (byte) 0x60, (byte) 0xfa, (byte) 0x97, (byte) 0x07, (byte) 0x12,
				(byte) 0x2d, (byte) 0x72, (byte) 0xe6, (byte) 0xc2, (byte) 0xb1, (byte) 0x0f, (byte) 0xe0, (byte) 0xc3,
				(byte) 0x3e, (byte) 0xc4, (byte) 0x30, (byte) 0xbf, (byte) 0xc8, (byte) 0x66, (byte) 0xe9, (byte) 0x79,
				(byte) 0xe3, (byte) 0xcc, (byte) 0x35, (byte) 0xb5, (byte) 0x54, (byte) 0x68, (byte) 0xd0, (byte) 0x4c,
				(byte) 0x9b, (byte) 0xff, (byte) 0x14, (byte) 0x21, (byte) 0x32, (byte) 0x78, (byte) 0x08, (byte) 0xbd,
				(byte) 0x63, (byte) 0x13, (byte) 0x47, (byte) 0xd5, (byte) 0x2a, (byte) 0xd3, (byte) 0xca, (byte) 0xdc,
				(byte) 0x6d, (byte) 0x38, (byte) 0xd9, (byte) 0xf9, (byte) 0x34, (byte) 0x0e, (byte) 0x73, (byte) 0x82,
				(byte) 0x46, (byte) 0x04, (byte) 0x62, (byte) 0xa2, (byte) 0xe8, (byte) 0xc9, (byte) 0x4f, (byte) 0xb2,
				(byte) 0xb3, (byte) 0xb6, (byte) 0x99, (byte) 0x2b, (byte) 0x7c, (byte) 0x37, (byte) 0x96, (byte) 0x7f,
				(byte) 0x8c, (byte) 0x22, (byte) 0x5f, (byte) 0x77, (byte) 0xf7, (byte) 0xe5, (byte) 0x17, (byte) 0xed,
				(byte) 0xe1, (byte) 0x6b, (byte) 0x8a, (byte) 0xf6, (byte) 0x80, (byte) 0xd1, (byte) 0x7d, (byte) 0xb9,
				(byte) 0x36, (byte) 0x05, (byte) 0xdf, (byte) 0x6c, (byte) 0x3a, (byte) 0x51, (byte) 0xea, (byte) 0x57,
				(byte) 0x94, (byte) 0x88, (byte) 0x06, (byte) 0xac, (byte) 0xc5, (byte) 0x2c, (byte) 0x11, (byte) 0xba,
				(byte) 0xcd, (byte) 0x9a, (byte) 0x2f, (byte) 0x20, (byte) 0xbb, (byte) 0x9f, (byte) 0xef, (byte) 0x8e,
				(byte) 0x71, (byte) 0x6e, (byte) 0x1b, (byte) 0x84, (byte) 0xb0, (byte) 0xcf, (byte) 0x28, (byte) 0xf2,
				(byte) 0xab, (byte) 0xd6, (byte) 0x16, (byte) 0x45, (byte) 0xa7, (byte) 0x83, (byte) 0x01, (byte) 0x02,
				(byte) 0x2e, (byte) 0x3b, (byte) 0x75, (byte) 0x9e, (byte) 0xa0, (byte) 0xa9, (byte) 0xa1, (byte) 0x7e,
				(byte) 0xcb, (byte) 0x74, (byte) 0x81, (byte) 0x91, (byte) 0x0b, (byte) 0x86, (byte) 0x44, (byte) 0x42,
				(byte) 0x3f, (byte) 0x15, (byte) 0x24, (byte) 0x31, (byte) 0x69, (byte) 0xfd, (byte) 0xce, (byte) 0x7a,
				(byte) 0xe2, (byte) 0x1c, (byte) 0xb4, (byte) 0x8b, (byte) 0x1f, (byte) 0x6a, (byte) 0x65, (byte) 0x7b,
				(byte) 0xe4, (byte) 0xf4, (byte) 0xf5, (byte) 0xde, (byte) 0x18, (byte) 0xfb, (byte) 0xdd, (byte) 0xf0,
				(byte) 0x43, (byte) 0x09, (byte) 0x53, (byte) 0xd4, (byte) 0x92, (byte) 0x8f, (byte) 0x9d, (byte) 0x9c,
				(byte) 0x59, (byte) 0x00, (byte) 0x3d, (byte) 0xa3, (byte) 0x41, (byte) 0xdb, (byte) 0x55, (byte) 0x95,
				(byte) 0x40, (byte) 0xc7, (byte) 0x49, (byte) 0xfc, (byte) 0x0a, (byte) 0xa4, (byte) 0x10, (byte) 0x64,
				(byte) 0x6f, (byte) 0x4b, (byte) 0xda, (byte) 0xeb, (byte) 0xee, (byte) 0xb8, (byte) 0xa8, (byte) 0xec,
				(byte) 0xbe, (byte) 0x5e, (byte) 0xc0, (byte) 0xc1, (byte) 0x4e, (byte) 0x33, (byte) 0x52, (byte) 0x58,
				(byte) 0x0d, (byte) 0x98, (byte) 0x90, (byte) 0xbc, (byte) 0x25, (byte) 0xfe, (byte) 0x48, (byte) 0x5d,
				(byte) 0xd8, (byte) 0x23, (byte) 0x03, (byte) 0x3c, (byte) 0x39, (byte) 0x87, (byte) 0xf8, (byte) 0x93,
				(byte) 0xe7, (byte) 0xd2, (byte) 0x5b, (byte) 0xf3, (byte) 0x29, (byte) 0x61, (byte) 0xd7, (byte) 0x1e,
				(byte) 0x27, (byte) 0x85, (byte) 0x89, (byte) 0x50, (byte) 0x67, (byte) 0xb7, (byte) 0x56, (byte) 0xaf,
				(byte) 0x4d, (byte) 0x0c, (byte) 0xa6, (byte) 0x1d, (byte) 0x4a, (byte) 0x70, (byte) 0xad, (byte) 0xa5,
				(byte) 0x8d, (byte) 0xf1, (byte) 0x19, (byte) 0x1a, (byte) 0xaa, (byte) 0xc6, (byte) 0x5c, (byte) 0x26,
				(byte) 0x5a };

		private byte s = (byte) 0xde;

		public Spi() {
			long seed = System.nanoTime();
			byte[] s = new byte[4];
			s[3] = (byte) (seed & 0x000000ff);
			s[2] = (byte) ((seed & 0x0000ff00) >> 8);
			s[1] = (byte) ((seed & 0x00ff0000) >> 16);
			s[0] = (byte) ((seed & 0xff000000) >> 24);
			engineSetSeed(s);
		}

		@Override
		protected byte[] engineGenerateSeed(int numBytes) {
			byte[] result = new byte[numBytes];
			engineNextBytes(result);
			return result;
		}

		@Override
		protected void engineNextBytes(byte[] bytes) {
			synchronized (this) {
				for (int i = 0; i != bytes.length; i++) {
					s = P[(s + P[n & 0xff]) & 0xff];
					bytes[i] = P[(P[(P[s & 0xff]) & 0xff] + 1) & 0xff];
					byte temp = P[n & 0xff];
					P[n & 0xff] = P[s & 0xff];
					P[s & 0xff] = temp;
					n = (byte) ((n + 1) & 0xff);
				}
			}
		}

		@Override
		protected void engineSetSeed(byte[] seed) {
			if (seed != null && P != null) {
				for (int m = 0; m < seed.length; m++) {
					s = P[(s + P[n & 0xff] + seed[m]) & 0xff];
					byte temp = P[n & 0xff];
					P[n & 0xff] = P[s & 0xff];
					P[s & 0xff] = temp;
					n = (byte) ((n + 1) & 0xff);
				}
			}
		}
	}

	private static final long serialVersionUID = 4516013411867308772L;

	public VMPCRandom() {
		super(new Spi(), (new SecureRandom()).getProvider());
	}
}
